The present invention relates to an apparatus for removing ghosts of television signals with a data processing for controlling filters.
Description of the Related Art
In a television (TV) receiver, a TV radio wave transmitted from a broadcasting station is converted into electric signals at a receiving antenna and is then converted into TV signals by a tuner. A TV radio wave reaches an antenna via a plurality of paths by some shielding or reflecting in addition to its direct arrival.
The radio wave repeatedly reflected has suffered a delay in time and a change in intensity compared with the radio wave directly reached. When reproducing on a TV screen, this reflected radio wave may often produce ghosts. A plurality of conventional ghost removal apparatuses have been developed, as disclosed in Japanese Patent Laid-Open Publication Nos. 56-69974, 3-117273, and 3-132166.
In such conventional ghost removal apparatuses, the ghosts are removed using a ghost removal reference signal shown in FIG. 1. In that case, a TV signal having much more noise, as shown in FIG. 2, is received, after the ghost removal, the frequency characteristic of the TV signal is shown in FIG. 3. A hatching 18 in FIG. 2 and a hatching 19 in FIG. 3 show noise included in the TV signal received. A hatching 20 in FIG. 3 shows noise emphasized by removing the ghosts.
In the conventional ghost removal apparatuses, when the ghosts are removed, the frequency characteristic of the TV signal is made to be an ideal characteristic. Accordingly, the high frequency area of the image signal is emphasized and the noise is thus emphasized in a receiving area having a weak electric field intensity. Further, with a transparent band of a cutoff frequency equal to or less than 4 MHz, a color ghost cannot be removed.